AML patients with relapsed and refractory disease have very poor outcomes. Sequential azacitidine and lenalidomide was recently shown by the PI of this study to be well-tolerated and effective in elderly, treatment naïve AML patients. Observations from this study and others that have piloted this combination have suggested that patients who received and failed prior treatments may also respond to this regimen. Therefore, the sequential combination of azacitidine with lenalidomide could potentially improve outcomes for relapsed and refractory AML patients by providing them with a treatment option that is tolerable and potentially clinically synergistic. To determine the efficacy of this combination in this population, we will pilot this phase 2 study.